add a11y epic to theme

Why is this change being made?

The work being done in the first a11y category epic brings actionable data to potentially every MR with just a template include in the gilab-ci.yml. That fits into our do powerful things easily theme pretty well I think.

Does this MR meet the acceptance criteria?

Conformity

• Added description to this MR explaining the reasons for the proposed change, per say-why-not-just-what